If a parent class defines a parameterless constructor, is it necessary to call super ()?

Is it necessary to call super() if a Parent class defines a no-argument constructor?

on any condition , The first line of the constructor Must be a call to the constructor of the parent class . in other words , Every time you create an instance of a subclass , Will create a new instance of the parent class in memory .

Default constructor - Is a parameterless constructor , If the class does not provide any constructors , The compiler generates it automatically . There is no difference between the default constructor and the parameterless constructor that you can add to your class yourself .

If a parent class has a parameterless constructor （ Whether it is declared manually or provided by the compiler ）, The compiler will be able to add super() a line .

If the parent class Only parameterization Constructor for , You must be in the constructor of the subclass Add calls manually super(name, salary) As the first line , Otherwise the code will not compile .
 

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for example :

Person There is no claim to extend anything , But by default it extends Object class , There is one in this category Parameterless constructor . therefore , If you decide to create it manually Person Constructor for , you There is no need to add super();, The compiler will handle it .

stay Employee Class in the constructor ,super(); This line is optional .

But for Manager Category , To compile , Its first line Must call super(name, salary);. You must call the parameterized constructor of the parent class with the appropriate parameters .

public class Person {
    public Person() {
        super(); // optional, can be added by the compiler
    }
}

public class Employee extends Person {
    protected String name;
    protected int salary;
    
    public Employee(String name, int salary) {
        super(); // optional, can be added by the compiler
        this.name = name;
        this.salary = salary;
    }
}

public class Manager extends Employee {
    public Manager(String name, int salary) {
        super(name, salary); // this line is mandatory
    }
}